In general, metal sheets of tin-free steel (TFS) and aluminum used for food cans are painted. The painting method has the problem of complicating a baking step, requiring much treatment time, and discharging a large amount of solvent. In order to resolve the problem, resin-coated metal sheets including thermoplastic resin films fused to the metal sheets under heating have been developed and now industrially used mainly as raw materials for beverage cans.
However, when a general resin-coated metal sheet is used for food cans, there occurs the problem that the contents strongly adhere to the inner surface of a vessel and thus cannot be easily taken out. This problem is closely related to consumer eagerness to buy and is thus a very important problem in maintaining consumer eagerness to buy. However, for conventional resin-coated metal sheets for containers, there are very few investigations of improvement in the ease of release of contents.
In Japanese Unexamined Patent Application Publication No. 2001-328204, the inventors have previously proposed, as a measure for improving the content release property, a metal plate laminated with a polyester resin containing specified wax.
This technique can secure a high property for high-fat contents with low adhesiveness, such as meat, eggs, hydrocarbon, or mixtures thereof, and can produce a certain result.
However, for contents with a high protein content, such as luncheon meat and tuna, the excellent content release property cannot be sufficiently secured because of high adhesiveness.
The present invention has been achieved for solving the above-mentioned problem, and an object of the present invention is to provide a resin-coated metal sheet for containers which has the excellent release property for contents with a high protein content.